1. Field of the Invention
This invention relates to well packers which may be set and reset without retrieval to the surface in various well applications such as injection, production, and disposal wells.
2. History of the Prior Art
It is well known in the well art, and particularly in the oil and gas industry, to use well packers in the bore of a well around the well tubing to seal the annulus between the well tubing and the well bore wall for isolating one or more vertical portions of the well bore. Well packers are used in testing, treating, and producing wells and in disposal well applications. These various and diverse systems employing well packers involve a wide range of depths at which the packers are used, environments which may produce extremes of high temperature and pressure as well as corrosive fluids, brine solutions, water, steam, and other natural formation fluids and fluids used in treating and producing wells. These various applications require a maximum of pressure sealing and corrosion resistance when left in place over long periods of time. In addition to the need for functioning in extreme hostile environments, the high cost of running, setting, and pulling packers in wells which requires handling equipment at the surface, as well as substantial periods of shut-down time, make it highly desirable to use packers capable of release and reset within a well bore without removal. It is particularly desirable for such a packer to be simple in construction with a minimum number of parts utilizing such features as one-piece locking slips, wherein one end of such slips is set initially before fully expanding the annular seal assembly prior to setting the slips to achieve maximum leak-free seals. Well packers capable of performing these desired functions, particularly for service under the adverse conditions described, require very high quality expensive materials which make such packers quite costly to manufacture. Thus, it is also desirable to reduce the physical size, particularly the length, of such special application packers to minimize the use of the necessary expensive materials, thereby reducing the cost of the packers. Typical well packers having some features in common with the present invention, but however, lacking the particular improvements of the present invention are shown in the following U.S. Pat. Nos. 3,467,184; 4,296,806; 4,524,825; and 4,671,354.